Approx 100 mm (4") diameter.
SpaceX CRS-11, also known as SpX-11, is a current cargo resupply mission to the International Space Station, launched successfully on 3 June 2017. The mission was contracted by NASA and is being flown by SpaceX. The mission utilized a Falcon 9 launch rocket and reuses a Dragon V1 cargo vessel that was previously flown on the CRS-4 mission.
CRS-11 is the penultimate of the first twelve missions awarded to SpaceX under the CRS contract to resupply the International Space Station.